The elastic properties of conducting vessels in vertebrates are determined, to a major extent, by the ratio of elastin to collagen. Under normal conditions, this ratio is dictated by the need to maintain the elastic modulus in a range that is best able to provide capacitance and pulse smoothing in a pulsatile circulatory system. This elastic modulus can change as a result of aging or disease through the loss of elastin or an increase in collagen. The consequences are a stiffening and dilation of the vessel and loss of its ability to dampen the pulsations in blood flow. Changes in blood flow and pressure result, with hypertension being a biomarker for altered vessel function. This proposal is organized around understanding the relationship between arterial stiffening and blood pressure changes. Aim 1 will take advantage of mice where the elastin/collagen ratio has been reduced by inactivation of one copy of the elastin gene to study the relationship between arterial stiffening and the development of hypertension. Aim 2 will employ conditional and inducible elastin transgenes to change the elastic properties of the vessel wall at different times to investigate the reversibility of stiffness-related hypertension. Aim 3 will utilize gene expression profiling to identify individual genes, gene sets, and molecular pathways that change in response to vessel stiffness and alterations in blood pressure. Aim 4 will pursue several treatment strategies that modulate blood pressure and alter vessel compliance.